Circuit for miniature lamps



Aug. 17, 1948. c, E, ATKINS 2,447,304

CIRCUIT FOR MINIATURE LAMPS Filed March 20, 1946 l lllli l5 l5 l4 Z4 0 I Z6 5'5 30 I um um M azjhvAvlvAv 'A INVENTOR. @wii aaezw Patented Aug. 17, 1948 Carl E..Atkins,.Elgin, 1 11., assignor to Sun-Kraft, 1'

Inc., Chicago, 111., a corporation of Delaware Application March 20, 1946, Serial No. 655,700

This invention relates to a circuit forenergizing a gaseous discharge lamp, particularly an ultraviolet or therapeutic lamp. Heretofore a therapeutic or ultraviolet generator has been developed which employs a gaseous discharge lamp of the electrodeless type, which is energized by high frequency oscillating energy. Thisrenergy is derived from an electronic tubeoscillator circuit. In order to provide'an oscillatorcircuit of.

such simplicity and compactness that its com-1 ponents could be mounted in a space of restricted area, as for example in'the base of a lamp fixture, the oscillating circuit was energized from. ordi- I nary low voltage alternating current suchas obtained frorn the house circuit without the use.

of a-power transformer. Such circuits employ a rectifier filter system to provide. the directcurrent voltage for the plate or anode of the oscillator tube. The-direct current voltage supply ob-- tained from ,115 volt alternating current source is of the order of. 85 volts direct current. 4

It was therefore proposed to energize theoscillator tube directly from alternating current.

thereby obtaining peak anode voltage values 1.4 times greater than the R. M. S. of 115 volts.-.-1 The application. of an oscillator ,of this type to a gaseous discharge lamp, however, hasthe disadvantage of producing an obnoxious flicker. 1 Since, the voltage necessary for starting acdischarge in the gaseous discharge tube is greater than the voltage necessary to maintain it, the discharge tube is dark more than fifty per cent of the time. Where the radio frequency peak applied to a gaseous discharge lamp is obtained from analter nating current energized oscillator, erratic opera: tion occurs because the operation is not under,

steady state conditions;

In. accordance with the' present invention this J disadvantage is overcome by employing two simi-y lar oscillators energized in phaseopposition .from the alternating current line. ,.Thez gaseous dischargelamp is b of electrodes. The output circuits of the oscillators are connected to one of the electrodes of each pair at opposite ends of the gaseous discharge tube. Su'chan arrangementmaintains-a discharge through the lamp without flicker.

It is, therefore, an object of'this invention to provide an improved electrodeless gaseous dis.-'

charge tube and circuit therefor whereby the tube may beoperated in an improved manner from provided at each end witha pair.

astandard low voltage alternating current power supply.

It isa further objector the present invention torprovide means for supplying toa' gaseous-dis- I .7 Claims. (01. 315-171) charge tube high frequency oscillating energy derived from anelectronic-vacuum tube oscillator.

circuit energized directly, from astandard low voltage alternating. current-power, supply such. as the ordinary housecircuit.

It is astill further object of.the. present invention to provide an improved high frequency oscillating circuit arranged to have its vacuum tube directly energized from standard low voltage alternating current supplied-by the'ordinary house ci-rcuitll'without the use .of power transformers; rectifiers 'or filters and whichwill be. capable of energizing a gaseous. discharge lamp for therapeutic treatments and other analogous use.

Other and further objects andadvantages of the present invention will become apparent from the following description taken in connection with the accompanying drawihgwherein the figure is a schematic drawing of. a circuit ,constructedand operated in. accordance-with the invention.

' The presentinvention as'shown in.the figure employs an elongated tubular gaseous discharge lamp {which isprovided at each end with a pair of electrodes. The lamp 2 may be a quartz ultra- I violet ray lamp or a fluorescent,lam'p'associated with f a high vacuum which is filled with mercury vapor, argon, neon, helium, and krypton or other suitable rare gases and with asmall globule of mercury. In the preferred form the lamp 2, is provided with exterior electrodes so that the lamp isv commonly. referred to as being electrodeless.

The lamp 2. at .On e:.,end isprovided with a pair of electrodes! and fiwhich preferably are in the form of a. s-plitrir'igwhich'also may serve to support or hold. the lamp} in position ina suitble fixture. At the other. end-thetube 2. isprovided with. another pair of split electrodes 8 andlll High. frequency oscillating current is applied to the electrodes at'opposite ends of the tube 2 as derived from a. pair of vacuum. tube oscillators employing. vacuum, tubes 12 and I4. Thev vacuumtubes l2, and ,llare each preferably of the indirectly heated cathode type having an anode and a plurality ofl grids. A. suitabletype of tube for this purpose is identified as.50L6GT..

I The oscillators'each employ atan'lt circuit. inductor, the extremities of which are connected to opposite ends of the discharge lamp tube... Thus the one oscillator circuit; has a tank circuit inductorv I-6 'havingits ends connected-t0 thefelectrode s Arand B whereas the otherficircuit has an inductor 18 connected to the electrodes 6 and I8.

An intermediate point on the tank inductor I6. is;

connectedto oneoft the grids of the vacuum tube .I2 suchas the ridnearestthe anode. The intermediate point on the conductor I6 is also connected to one side of the alternating current power supply circuit such as the conductor 20. The other alternating current conductor 22 is connected to the intermediate point on the other oscillator inductor l8 and also to the grid nearest the anode of the vacuum tube M. The cathode of the vacuum tube is directly connected to the alternating current 22 whereas the cathode of the vacuum tube i4 is connected to the other alternating current conductor 20.

The remaining electrode of the vacuum tube 12 is connected to a grid condenser and leak circuit extending between one end ofthe .tank inductor l6 and the cathode. The grid therefore is connected to the common juncture between the grid condenser 24 and the grid leak 265' Sim- 4 ing current, means connecting the anodes of said vacuum tubes for energization in phase opposition from said source of alternating current, and means connecting the output of each oscillator circuit to said electrodes of said discharge tube.

2. A circuit for energizing a single gaseous discharge tube from a standard low voltage alternating current source, said tube having an elongated envelope provided with electrodes at the ends thereof, comprising a pair of vacuum tube I roscillators energized in phase opposition from a'source of alternating current, and means con- "Ynecti'ng the outputs of said oscillators to said electrodes oisaid discharge tube to energize said tube. during each half cycle of alternating current.

l 3. A circuit for energizing a gaseous discharge ilarly the grid of the vacuum tube I4 is connected to the common juncture of a grid condenser 28' and a grid leak 30 extending between one extremityjof thetank inductor l8 and the cathode of the vacuum tube 1 4. Where the vacuum tubes l2 and M are of the'type having a 50 volt filament for heating indirectly the cathodes, the two heaters may be connected in series with a small resistor 32fsothatthe series connected cathode heaters are connected across the alternating current conductors and 22. v H

From the foregoing it will be seenthat the anodes of the vacuum tubes I2 and I 4. arranged in two. similar oscillator circuits are energized from alternating current in phase opposition. The peak voltage applied to the'vacuurn tubes [2 and II has a value 1.4 times the R. M. 5. value of the standard low voltage alternating current power applied to the conductors 20 and 22. Thus the highfrequency oscillations developed by the vacuum tubes 12 and during successive half cycles have powervalues much greater than could be obtained if the alternating current supplied by the conductors 20 and 22 were rectified which would providea potential of 85 volts. By applyingjthe outputs of the oscillator tank inductors 60 and 18 to opposite ends of the discharge lamp.

2, the lamp willnot be extinguished during successive half cycles as would be the case, if only a single oscillator were employed. I I

In. the'preferred form the oscillator circuits employ vacuum tubeso f the type identified as 50L6GT having jheaters connected in series across the alternating current source with the value of the resistor 32 such that for the normal household voltage 115'volts, the cathode heaters are not subjected to excess voltage. The values of the tank circuit inductor, the grid condenser and the grid resistor are such that the operating frequency is at the selected frequency from among those frequencies assigned by the government for sciene tificihdustrial and medical purposes.

While the circuit as shown has employed vacuum tubes having 50 volt heaters for thecat hodes, it, of course, will be apparent thatwhen available othervtypes of tubes having 117 volt filaments may be. employed in which case each cathode heater will be directly connected across the alternating current supply line. Similarly other suitable variations are contemplated in the values and circuit arrangementshown without departing from the spirit and scope of the invention as delineated in the following claims.

This invention is hereby claimed as follows:

1. A circuit for energizing a single gaseous discharge tube with associated electrodes comprising a pair'bf vacuum tube oscillator circuits each including a vacuum tube, a source'of alternat- .tube by. means of electrodes from a standard low the tube comprising a pair of vacuum tube oscillator circuits including a, vacuum tube, a source of alternating current, means for energizing the anodes of'said vacuum tubes in phase oppositionfrom a source of alternating current, and means connecting the'output of each oscillator to one ofeach of said pairs of electrodes.

5. Acir'cuit for energizing'a gaseous discharge device having an elongated envelope provided at eachend with a pair of external electrodes comprising afpair of vacuum tube oscillator circuits each having a vacuum tube, a source of alternating current; a tank circuit inductor, means for energizing the anodes of said oscillator vacuum tubes-inphase opposition from a source of alternating current, and means connecting each tank 1 "inductor between one of the electrodes at each of'the ends of said gaseous discharge'device.

6. A circuit for energizing a gaseous discharge device having an elongated envelope provided with a pair of electrodes at each end thereof from a standard lowvoltage alternating current source comprising a pair of vacuum tube oscillators each having a. vacuum tube provided with a cathode and anode and a plurality of electrodes thereb et'ween, each oscillator circuit having a tank'circuit inductor connected to electrodes at opposite ends of said gaseous discharge device,

an intermediate point on said inductor being connected to a vacuum tube electrode and to one side of said source of alternating current, one end of said inductor being coupled to the remaining electrode of said vacuum tube, and means directly connecting the anode to the other end of said tank circuit inductor. h

'7. The combination comprising an elongated gaseous discharge device having a pair of external electrodes'ateach end, a pair of oscillator circuits each including a tank circuit inductor, 'a standard low voltage source of alternating current, and a vacuum tube having an 'indirectlyhea'ted cathode, a cathode heater, an anode, and a plurality means connecting the cathodes to 'oppositeisides of said alternating current source, means connect- REFERENCES CITED ing one electrode of each ofisaid vacuum tubes The following references are of record in the to opposite sides of said alternating current 1 source and to an intermediate point on the reof this patent spective tank circuit inductors, means connect- 5 UNITED STATES PATENTS ing the anodes to one end of each of 16 rgspectivg Number Name. Date inductors, means interconnecting t e 0 her en of each of the tank circuit inductors to the re- 2214441 Seaman et a1 Sept maining electrode in each vacuum tube, and FOREIGN PATENTS means interconnecting said tank circuit inductors 10 Number Country Date each to opposite ends of the external electrodes 435,025 Great Britain Sept 13, 1935 of said gaseous discharge device.

CARL E. ATKINS. 

